package cn.tedu.jsd2210.csmall.passport.filter;


import cn.tedu.jsd2210.csmall.passport.ex.ServiceException;
import cn.tedu.jsd2210.csmall.passport.security.LoginPrincipal;
import cn.tedu.jsd2210.csmall.passport.web.JsonResult;
import cn.tedu.jsd2210.csmall.passport.web.ServiceCode;
import com.alibaba.fastjson.JSON;
import io.jsonwebtoken.*;

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.context.SecurityContext;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.filter.OncePerRequestFilter;
import springfox.documentation.spring.web.json.Json;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

/**
 * <p>JWT过滤器</p>
 *
 * <p>此过滤器的主要作用</p>
 * <ul>
 *     <li>接收客户端提交的请求中的JWT</li>
 *     <li>尝试解析客户端提交的请求中的有效JWT</li>
 *     <li>将解析成功得到的数据创建为Authentication对象，并存入到SecurityContext中</li>
 * </ul>
 */
@Slf4j
@Component
public class JWTAuthorizationFilter extends OncePerRequestFilter {

    @Value("${csmall.jwt.secret-key}")
    private String secretKey;
    /**
     * JWT的最小长度值
     */
    public static final int JWT_MIN_LENGTH=113;
    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
        log.debug("JWT过滤器开始执行……");

        // 清空SecurityContext，避免【此前携带JWT成功访问后，在接下来的一段时间内不携带JWT也能访问】
        // SecurityContextHolder.clearContext();

        // 根据业内惯用的做法，客户端提交的请求中的JWT应该存放于请求头（Request Header）中的名为Authorization属性中
        String jwt=request.getHeader("Authorization");
        log.debug("客户端携带的JWT：{}", jwt);

        // 判断客户端是否携带了有效的JWT
        if(!StringUtils.hasText(jwt)||jwt.length()<JWT_MIN_LENGTH){
            // 如果JWT无效，直接放行
            log.debug("客户端没有携带有效的JWT，将放行，由后续的过滤器等组件继续处理此请求……");
            filterChain.doFilter(request,response);
            return;
        }
        //尝试解析JWT 并处理可能出现的异常
//        @ExceptionHandler
//        public JsonResult<Void> handleServiceException(ServiceException e) {
//            log.warn("程序运行过程中出现ServiceException，将统一处理！");
//            log.warn("异常信息：{}", e.getMessage());
//            // return JsonResult.fail(e.getServiceCode(), e.getMessage());
//            return JsonResult.fail(e);
//        }
        Claims claims=null;
        response.setContentType("application/json;charset=utf-8");

        try {
            claims = Jwts.parser().setSigningKey(secretKey).parseClaimsJws(jwt).getBody();
        } catch (ExpiredJwtException e) {
            PrintWriter writer=response.getWriter();
            String message="您的登录信息已过期，请重新登录！";
            log.warn("解析JWT时出现ExpiredJwtException,将响应错误信息:{}",message);
            JsonResult<Void> jsonResult=JsonResult.fail(ServiceCode.ERROR_EXPIRED,message);
            String jsonString = JSON.toJSONString(jsonResult);
            writer.println(jsonString);
            writer.close();
            return;
        }catch (MalformedJwtException e) {
            PrintWriter writer=response.getWriter();
            String message="非法访问!";
            log.warn("解析JWT时出现MalformedJwtException,将响应错误信息:{}",message);
            JsonResult<Void> jsonResult=JsonResult.fail(ServiceCode.ERROR_MALFORMED,message);
            String jsonString = JSON.toJSONString(jsonResult);
            writer.println(jsonString);
            writer.close();
            return;
        }catch (SignatureException e) {
            PrintWriter writer=response.getWriter();
            String message="非法访问!";
            log.warn("解析JWT时出现SignatureException,将响应错误信息:{}",message);
            JsonResult<Void> jsonResult=JsonResult.fail(ServiceCode.ERROR_SIGNATURE,message);
            String jsonString = JSON.toJSONString(jsonResult);
            writer.println(jsonString);
            writer.close();
            return;
        }catch (Throwable e) {
            PrintWriter writer=response.getWriter();
            String message="服务器忙，请稍后再次尝试！（开发过程中，如果看到此提示，请检查控制台的信息，并补充处理异常的方法）";
            log.warn("解析JWT时出现Throwable,将响应错误信息:{}",message);
            log.warn("异常类型:{}",e.getClass().getName());
            log.warn("异常消息:{}",e.getMessage());
            JsonResult<Void> jsonResult=JsonResult.fail(ServiceCode.ERROR_UNKNOWN,message);
            String jsonString = JSON.toJSONString(jsonResult);
            writer.println(jsonString);
            writer.close();
            return;
        }

        Long id = claims.get("id",Long.class);
        String username = claims.get("username",String.class);
        String authoritiesJsonString=claims.get("authoritiesJsonString",String.class);

        log.debug("解析JWT结束:id={},username={}",id,username);

        List<SimpleGrantedAuthority> authorities = JSON.parseArray(authoritiesJsonString, SimpleGrantedAuthority.class);
        log.debug("将JWT中的权限列表的JSON字符串解析为List<GrantedAuthority>类型，结果：{}", authorities);


        //创建Authentication对象
        LoginPrincipal loginPrincipal=new LoginPrincipal();
        loginPrincipal.setId(id);
        loginPrincipal.setUsername(username);

        Object principal=loginPrincipal;
        Object credentials=null;
        Authentication authentication=new UsernamePasswordAuthenticationToken(principal,credentials,authorities);
        log.debug("即将存入到SecurityContext中的Authentication对象：{}", authentication);


        //把 Authentication 对象放进 SecurityContext中
        SecurityContext securityContext= SecurityContextHolder.getContext();
        securityContext.setAuthentication(authentication);
        log.debug("已经将Authentication对象存入到SecurityContext");
        //放行
        log.debug("JWT过滤器执行完毕，将放行");
        filterChain.doFilter(request,response);
    }
}
